Did a search but couldn't find what I was looking for. Issue: Riding in a strait line I can stand up on the pegs and look down at the front tire and it's not tracking center with the beak, it's noticeably off, turned a couple degrees (say less than 5 degrees) to the left. First thought was to check the rear wheel alignment. Axle adjustment bolts were about 1mm difference (right side being the shorter). I readjusted and corrected for chain tension. Took it around the block and seemed better, but still not centered with the beak. Couldn't get a good look as it was getting dark. Has anyone else noticed something like this?
I agree with DPM ... plastics might not be best reference point ... esp. if you let the bike take dirt naps... On the other hand (and if Reaver finds this thread he'll be all over me ) sometimes I find I need something new to worry about, and the rear axle being "square" is something that has made the list. The machined marks on the axle blocks can not be trusted, and the jack screws have very coarse threads so "fine adjustment" is difficult so there are a number of methods to try to check the axle being true... I have a cheap knock-off of this tool and it works OK, but not super... http://www.motionpro.com/motorcycle/partno/08-0048/ This tool looks kinda cool, but I don't quite understand the "science" behind it and haven't had time to meditate over it... (yeah Reaver the anxiety closet overflows here ) http://www.proaligner.com/ A couple of companies make laser tools ... and then there's the homebrew setup here: http://www.advrider.com/forums/showthread.php?t=161521 I'll shut up now and go back to my coffee
Lasers.....at work the youngins use laser this and laser that...I use string lines and plumb bobs. I found that most bikes are built with the centre of the front wheel and the centre of the rear wheel completely independant of each other and the centre of the frame. When I bothered to take the time and align everything, the bike flicked from left to right through peg scraping turns with absolute ease. The skitishness under hard brakes disappeared. The front wheel still doesn't look like it's pointing straight if I stand up and look down at it. I just ignore it now.
No. I see what you're trying to do, you crafty old dog. I use the string line around the back tyre, wrap completely around at the rear just below axle height so it doesn't foul anything, then take both sides of the string forward down each side of the bike past the front wheel. Tyre off the rim is most accurate, but depending on the tread pattern, it works with tyre on. As you bring the 2 pieces of string together toward centre line, they will touch the edges of the rim (or tyre) toward the front just under the bash plate. This will accurately give you the direction your rear wheel is pointing in relation to the front. It helps if you have something you can weight the strings down with and leave them accurately in position. Now I plumb bob from various points on the frame to establish if the frame is vertical, and mark the points on the floor. The steering head is a good spot to start. A good 3 foot ruler comes in handy here as well. I measure across the lower frame and engine and try to plot out a centreline and check with straight edge ruler. Having plastics off the bike will help you ascertain if points of the main frame are vertical (or horizontal) using the plumb bob and a spirit level. Mark the point directly below the steering head once you have the frame as vertical as you can get it. Use this as the reference for the rear wheel pointing straight ahead. It isn't perfect, because a frame that's bent can play with the end result, but if your frame is bent it's as good as you'll get it. I usually use my rachet straps off the main frame to the garage rafters to allow for unimpeded string lining due to centre stand etc. I had my DR 650 rigged up with 2 x 3 foot rulers, plumb bob, horizontal string off the wheels, and points marked out in texta all over the garage floor to discover that the frame is no where near straight, and that the front wheel was mounted about 15mm to left of centre, and the rear wheel about 10mm to the right. I adjusted the spokes to get the wheels closer to centre line, and adjusted the rear wheel axle clamps so that the wheel points directly at the centre of the steering head. My F800 has the rear sub frame bent to the right by 15mm, with a twist to the right that takes it about 4 degree off horizontal. I haven't got around to getting as technical with the BMW as I did with the DR. But the differences to the DR's on road handling were quite noticeable. I've noticed things like the footpegs are not equidistant from centre line on any of the bikes I've checked. Plus, "straight" is a relative term when it comes to mass produced frames.
If you are riding around and it appears that the front tire is not aligned (and you are using the beak as a point of reference) your bike would be trying to drive off the road. If you said, your handle bars were not aligned while riding then I'd say your wheel/forks may be off. Given the rake, the front will try to spin true and any bends and or twists in the fork would be evident in the handle bars and not the tire itself.
I'm surprised you even leave the house Woody. At least you left your foil helmet at home when we went for pizza. The machined marks are also used on the S1000RR. Just sayin'. There are lots of methods to check and adjust alignment. It can take an hour or so. One drop, one big pothole or even a chain adjustment can negate all of your efforts not to mention how you load your gear. If you're standing on the pegs looking down then you need to make many passes and on different roads to get a positive result. The slope of the road and cross winds will affect things. My old boss at Motorrad had a number of race bikes. He'd spend hours and days just nit picking trying to achieve perfection. Then on race day he'd lose big time and blame the bike. Repeat for over 10 yrs. I just thought if he'd spend like 1% of the fussing time learning how to ride he'd be much further ahead. Yes alignment is important for many reasons. Start with the basics like checking that the forks are straight and then go as detailed into it as your personality demands. There are a few alignment threads within the first two pages. As for me, I need to worry about the bigger things like changing a tire and coolant before Saturday's 13K km NA trip to the Pacific and beyond on our twins. And NO Woody, we aren't bringing a support vehicle.
I've got one and it works and is simple and quick to use. The machined edge opposite the clamp screw is parallel to the rod. So you just clamp the thing on your sprocket, with the rod extended out over the chain and sight down it. It's pretty easy to see if the alignment is off. Just don't forget to remove it before moving the bike or it'll end up somewhat less accurate I used to use a homemade gizmo which consisted of a nice straight piece of welding rod about 3' long, with a zip tie around it with the free end sticking out and clipped at an angle. The other end of the rod had a point ground on it, and was bent at a right angle. You just use it to measure along the swingarm from its pivot point to the centre of the axle, on both sides, sliding the ziptie along to get the length of one side. But I lost that somewhere (who knows where) and happened to see the MP tool in a store, so I bought one. My friends say I have more money than brains
Reaver has nailed it. It's interesting to check it accurately just once to figure out any "zeroing" you need, or after a big get off. But after that it's purely academic. I've heard stories from mates that race about blokes who just couldn't leave the technical stuff alone, yet never won and blamed the bike. It reminds me of an old saying "Stupidity is - If you do the same thing the same way and expect a different result".
